Implantable neurostimulation systems have proven therapeutic in a wide variety of diseases and disorders. Pacemakers and Implantable Cardiac Defibrillators (ICDs) have proven highly effective in the treatment of a number of cardiac conditions (e.g., arrhythmias). Spinal Cord Stimulation (SCS) systems have long been accepted as a therapeutic modality for the treatment of chronic pain syndromes, and the application of tissue stimulation has begun to expand to additional applications such as angina pectoralis and incontinence. Deep Brain Stimulation (DBS) has also been applied therapeutically for well over a decade for the treatment of refractory chronic pain syndromes, and DBS has also recently been applied in additional areas such as movement disorders and epilepsy. Further, in recent investigations Peripheral Nerve Stimulation (PNS) systems have demonstrated efficacy in the treatment of chronic pain syndromes and incontinence, and a number of additional applications are currently under investigation. Furthermore, Functional Electrical Stimulation (FES) systems such as the Freehand system by NeuroControl (Cleveland, Ohio) have been applied to restore some functionality to paralyzed extremities in spinal cord injury patients.
Each of these implantable neurostimulation systems typically includes an electrode lead implanted at the desired stimulation site and an implantable pulse generator (IPG) implanted remotely from the stimulation site, but coupled either directly to the electrode lead or indirectly to the electrode lead via a lead extension. Thus, electrical pulses can be delivered from the IPG to the electrode lead to stimulate the tissue and provide the desired efficacious therapy to the patient.
In certain scenarios, it may be desirable to track the physical activity (e.g., activity level or body manipulations) of the patient that has received the implantable neurostimulation system, which provides an indication of the efficacy of the therapy provided by the stimulation system; that is, the more efficacious the therapy, the more diurnally active the patient will be. Thus, knowledge of the physical activity of the patient over a period of time in which therapeutic stimulation is applied to the patient may be used by a physician or clinician to prescribe drugs, reprogram or upgrade the IPG, or implement or modify other therapeutic regimens (such as physical or occupational therapy). Knowledge of the physical activity of the patient may also be used to adapt the therapy provided by the stimulation system in real time, so that the stimulation is consistently provided to the patient at an efficacious and/or comfortable level.
There, thus, remains a need for an improved method and system for determining the physical activity of a patient in which a neurostimulation system has been implanted.